This supports having a commit sha backwords compat so you can either
specify branch or branch + commit
Also support for stripping out refs/meta/ from branch url
Example
This is an example with just branch
https://phabricator.wikimedia.org/r/branch/mediawiki/core;master;
This is an example for branch + sha
note
Requires https://gerrit.wikimedia.org/r/#/c/301849/ also to be merged at the same time
Bug: T137354
Change-Id: Ic5c8e8c3bde16e62d014065c5814853f5b9c9411